Based on the results of the HER2CLIMB trial (NCT02614794), combination therapy with tucatinib plus trastuzumab plus capecitabine was approved by the Food and Drug Administration (FDA) for the treatment of adult patients with unresectable, advanced, or metastatic HER2-positive breast cancer, including patients with BM, who have received at least one regimen of anti-HER2 therapy for metastatic breast cancer8,9. This evidence concerns the gene ERBB2 and breast carcinoma.